Some electric fuses have fusible elements which perform only one function, whereas other electric fuses have fusible elements which perform dual functions. One example of an electric fuse that has a fusible element which performs only one function is an electric fuse that is connected in series relation with a circuit breaker; and the only function to be performed by the fusible element of such an electric fuse is to open the circuit in response to a heavy overcurrent or short circuit. Another example of an electric fuse that has a fusible element which performs only one function is an electric fuse which has a spring-biased connector or a large mass of solder that can respond to a prolonged low overcurrent to open the circuit; and the only function to be performed by the fusible element of such an electric fuse is to open the circuit on a heavy overcurrent or short circuit. One example of an electric fuse that has a fusible element which performs a dual function is a renewable electric fuse that has a fusible element which is able to open the circuit in response to a prolonged low overcurrent or to a heavy overcurrent or short circuit. Another example of an electric fuse that has a fusible element which performs a dual function is an electric fuse that has a silver or copper fusible element with a mass of tin riveted or bonded to it. An electric fuse which has a spring-biased connector or a large mass of solder that can respond to a prolonged low overcurrent to open the circuit is referred to as a dual-element electric fuse, and, similarly, an electric fuse that has a silver or copper fusible element with a mass of tin riveted or bonded to it is referred to as a dual-element electric fuse.